With many of the apps and web services I use, I’m inclined to get excited over new features–or at least to approach them with an extremely open mind. Instagram is different. I like the photo-sharing social network so much just as it is that my instinct is to get worried about changes. Especially major, app-redefining changes.

So when it turned out that the news at Facebook’s media event this morning was indeed about video on Instagram, I gulped. But after Instagram’s Kevin Systrom explained how video will work and showed it off a bit, I calmed down, at least for the moment.

I’ve always considered Instagram to be a Garden of Eden among social networks–pure, unspoiled and joyful–and now I think it’s possible that video won’t be a blight. It might even make Instagram better.

The new feature is available in both the iPhone and Android versions of the app, both of which have now been updated. You can also view videos on Instagram’s website.

One of the fascinating things about video-based social networking is that it’s not entirely obvious how to make it appealing rather than a hassle. A bunch of startups have tried it without going anywhere. Others, such as Socialcam, have had some success. And Vine, which is now owned by Twitter, seems to be really catching on.

Video on Instagram is a tad reminiscent of other services without being a clone of anything that’s already out there. Here are the basics:

Videos show up in your stream alongside still photos. They auto-play when you stop on them them (but you can disable that).

After you press the camera icon on Instagram’s main screen, you go into still-picture mode, as usual–but can tap a videocamera icon to shoot video.

They can be up to fifteen seconds long, a length Systrom said the company settled on after experimenting with others and having a “Goldilocks moment” when it tried fifteen seconds.

The fifteen seconds can be made up of multiple clips–as in Vine, the camera only shoots when you hold your finger on the shutter button.

There are thirteen new filters designed to make video look good.

They only play once, not in a GIF-like loop.

A stabilization feature called “Cinema” — available on the iPhone 4S and 5 — is designed to remove jitters automatically. Systrom said it was designed with the help of top computer scientists, called it “completely mind-blowing” and said that it “changes everything.”

As with the rest of Instagram, there’s a team devoted to preventing porn, which leverages the considerable resources Facebook devotes to that effort.

Systrom spent almost as much time explaining how hard Instagram worked to make the video features simple and beautiful as he did actually detailing how they worked. During the event, I downloaded the new iPhone app and fooled around with it–here’s one video I shot–and it does indeed look thoughtfully done. Instagram still looks like the Instagram I love, not like a photo service with video bolted on.

Still, no matter how artfully Systrom and company did their work, they’re not the folks who will ultimately determine how video changes the app. The ones who will are the 130 million people who use Instagram each month. They might embrace video; they might use it surprisingly little; they might be just as clever with video clips as they are with still images, or they might shoot stuff that’s mundane, crass or simply not, well, Instagrammy.

We won’t have to wait long until we get a sense of what Instagram will feel like from now on–in fact, my Instagram stream is already full of video. If you’ve tried the new version, I’d love to know what you think.